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Have you ever done a Silnylon project like this one? If so could you compare for the DIY'ers the pros and cons of the two material..

I once made an 8' x 11' Japanese kite out of approximately 2 oz. ripstop sail cloth (presumably with some sort of coating, but not waterproof). It was bridled with 17 bridle lines, each 100 ft. long, attached to a main flying line of 1/8" braided nylon. It also had many carbon fiber arrow blanks making up a network of spars. The whole thing (bridles, spars, main line) was designed to evenly distribute the forces a sail of this size could generate. It took five people (wearing gloves) to fly it. It flew well on almost no breeze at all. One gusty day I managed to wrap it around the tv antenna on top of the Harvard Business School (retrieved safely, however). I have thought of this kite a number of times while making a cuben sail that's 12% bigger but weighs less than 6 ounces. (Oh, if I'd had cuben in my kite-building days! )

But back to reality: there are logistical issues of dealing with large areas of fabric or cuben that are exactly the same. It helps to roll the sail/kite/tarp to leave accessible just the part you want to sew or tape. If you have a long, narrow work table, it helps to have a large open area nearby where you can roll or fold your project so it fits on the work table. Breezes can be a nuisance.

Working with cuben is not more difficult than working with silnylon, but a number of the challenges are different, so be prepared to start a bit lower on the learning curve. By the way, one of those challenges is money.

Cuben Tarps

Wow, thank you David and Mountainfitter for your Cuben engineering input.
It seems a great percentage of "hangers" on the Forum are DIY'ers

I read on Backpacking Light's site, one shouldn't sew Cuben. Thus, I now have a pretty good sewing machine for sale?

I would very much appreciate some close-up pix of the pull-outs. ie: reinforcment engineering knowledge for we DIY'ers.

What a great bunch of guys we ''hangers'' are ... huh?
Thank you Al Gore for inventing the internet that we can all chat and learn ...

And, MountainFitter, do you have a selling price yet? When I saw Backpacking Light's Cuben Tarp retail price, I just about ... Well anyway, My wife said to buy "gold" instead .................... and she'd carry my backpack .............

Haha... Gold is heavier Come to think of it, its priced closer to silver at $18.80 an oz... That is probably the biggest drawback cuben has is the cost. Its about 4x the cost of really good quality Nylon 6,6 Made in USA Silnylon and about 10x the cost of Asian stuff most big companies use.. I wouldn't sell your sewing machine just yet... Sewing using the right stitch type and length combined with tape can help for peel strength..

I'm just finishing my first cuben tarp, about 9' x 11'. It has one center seam, taped with 1" wide 3M 9460 tape, pre-primed with 3M Primer 94. The edge seams are reinforced by being turned over once and taped (same materials, but 1/2" wide.) Next I will attach toggle-reinforced tie-outs (a la Gnome). Then comes the hard part: waiting a week before trying it out so the taping can "cure", that is, reach maximum strength.

What I've learned so far (after 51' of taping):
1) The easiest way to cut cuben accurately, especially near the edges where the HMPE fibers stop, is with a soldering iron and a metal straightedge on masonite, formica, or glass.
2) Using a printing brayer or laminate roller is the best way to press the tape after it's properly positioned.
3) The easiest way to remove the backing strip from adhesive transfer tape is with the cuben pieces already pressed together. The backing strip folds back and slides out of the space between them and the cuben bonds immediately (where it's supposed to).
4) If the adhesive on the tape touches anything except the surfaces you're bonding, it becomes unusable.
5.) If you want to tape edge seams 1/2" wide, don't try to cut 1" tape in half lengthwise. (I did it, and lived to tell the tale, but will not hesitate to spend $24 on a roll of 1/2" tape if I decide to do it in the future.)
6) The Primer 94 is available in 1/2 pint cans (and bigger), and also in 66 ml. ampules. I got the 1/2 pint size, but it goes a long way.
7) There's a knack to handling this stuff, but it doesn't take too long to learn. Your second or third tarp should start looking pretty good.

I have been working on mine this weekend also. I completely agree with everything that you have listed. So I have only taped the ridgeline, I am still waiting on some parts to do the tieouts. I would love to see how you did yours. I am doing a modified toggle arrangement also. I found the seam very strong and have cleaned it with denatured alcohol to remove some of the excess 94 and tape.

I'm still trying to explain it to myself. In other words, I'm figuring it out as I go along. Gnome is the one with experience. Here is his description of his tie-outs: "I use gorilla tape- cuben -tape with the carbon fiber tube, (1/8 in diam )in the U of the tape. Then I poke a hole in the center of the tube in the tape and tie the cord, instead of threading the tie out thru the tube, works well on edges.Distributes the load well."

I used to have some 1/8" carbon fiber tube, but can't find it, so I've resorted to cutting up some old aluminum tent poles which are a bit over 5/16" diameter. I could have used chopped up knitting needles (a good source for toggle material), but the smaller size needles aren't hollow, so they're heavier. Instead of Gorilla tape, I'm using some DIY cuben tape, made by cutting 2" strips of cuben and applying two 1" strips of 9460 adhesive transfer tape. I expect the larger diameter of the tube could subject the tape to peel force rather than shear force where it leaves the tube and attaches to the two sides of the tarp so I plan to hand stitch it close to the tube. Right now the tape is made up, but I haven't finished sanding the cut ends of the tubes. I will take pictures and post later. I also plan to compare my cuben tape to Gorilla tape by making a test strip with a connector of each type on the ends. Then I'll pull it with a come-along to see which one breaks. In the meantime I've put the tarp in my greenhouse to cook it a bit and speed curing time for the taped seam and edges. Stay tuned.

1) The easiest way to cut cuben accurately, especially near the edges where the HMPE fibers stop, is with a soldering iron and a metal straightedge on masonite, formica, or glass.

WV I bought one of those cutting wheels with a 16" long self healing mat to trim the selvage. I used a long straight edge Iand a fine line sharpie to define the cut and used the grid on the mat to follow my cut. The cutting wheel cut clean thru the material on the first pass and it made a clean line.